Multiple combined indirect procedure for the surgical treatment of children with moyamoya disease. A comparison with single indirect anastomosis with direct anastomosis

[Moyamoya disease in adults: treatment methods in modern era]

Moyamoya angiopathy is a chronic progressive cerebrovascular disease characterized by stenosis and occlusion of the distal segments of the internal carotid arteries and/or proximal segments of the middle and anterior cerebral arteries, with a gradual compensatory restructuring of the cerebral circulation to the system of the external carotid arteries. Today, the main treatment method for Moyamoya angiopathy is surgical revascularization of the brain. A search and analysis of publications on the treatment of adult patients with Moyamoya angiopathy was carried out in the PubMed and Medscape databases over the past 10 years. We present a case of an adult female patient with a hemorrhagic form of Moyamoya angiopathy stage IV according to J. Suzuki, who underwent staged combined revascularization of both cerebral hemispheres. Surgical revascularization included the creation of a low-flow extra-intracranial shunt combined with a combination of indirect synangiosis. The combination of direct and indirect methods of surgical revascularization enables to achieve the development of an extensive network of collaterals and fully compensate for cerebral circulatory disorders both in the early and late postoperative periods, which is confirmed by instrumental diagnostic data. Combined revascularization is the most effective modern method of treating patients with Moyamoya angiopathy due to the complementary influence of direct and indirect components of revascularization.

The evolution of pediatric neurosurgery: reflection of personal experience of the last half-century

OBJECTIVES

In the past 50 years, pediatric neurosurgery has made tremendous strides, and gained its own identity as a distinct subspecialty. I have personally observed this progress and evolution in pediatric neurosurgery in multiple dimensions, which are described based upon my own experience and reflection.

METHODS

The development and evolutions of multiple domains of pediatric neurosurgery, including neuroimaging, hydrocephalus, pediatric brain tumor, spinal dysraphism, craniosynostosis, vascular malformation, functional neurosurgery and spinal disorders were reviewed and commented on based upon my own experience and reflection.

RESULTS

The field of pediatric neurosurgery has grown in all aspects of diagnosis and therapy owing to the introduction of computers, innovative techniques and technologies and new discoveries of scientific data including molecular investigations.

CONCLUSION

A minimally invasive approach and molecular target therapy are a current trend. The past half century's clinical experience and advances in biomedical knowledge and techniques provide foundation for further improvement in the care of children of the next generation. Prospective artificial intelligence will likely promote further advances in pediatric neurosurgery.

Surgical revascularizations for pediatric moyamoya: a systematic review, meta-analysis, and meta-regression analysis

INTRODUCTION

There is no clear consensus regarding the technique of surgical revascularization for moyamoya disease and syndrome (MMD/MMS) in the pediatric population. Previous meta-analyses have attempted to address this gap in literature but with methodological limitations that affect the reliability of their pooled estimates. This meta-analysis aimed to report an accurate and transparent comparison between studies of indirect (IB), direct (DB), and combined bypasses (CB) in pediatric patients with MMD/MMS.

METHODS

In accordance with PRISMA guidelines, systematic searches of Medline, Embase, and Cochrane Central were undertaken from database inception to 7 October 2022. Perioperative adverse events were the primary outcome measure. Secondary outcomes were rates of long-term revascularization, stroke recurrence, morbidity, and mortality.

RESULTS

Thirty-seven studies reporting 2460 patients and 4432 hemispheres were included in the meta-analysis. The overall pooled mean age was 8.6 years (95% CI: 7.7; 9.5), and 45.0% were male. Pooled proportions of perioperative adverse events were similar between the DB/CB and IB groups except for wound complication which was higher in the former group (RR = 2.54 (95% CI: 1.82; 3.55)). Proportions of post-surgical Matsushima Grade A/B revascularization favored DB/CB over IB (RR = 1.12 (95% CI 1.02; 1.24)). There was no significant difference in stroke recurrence, morbidity, and mortality. After meta-regression analysis, year of publication and age were significant predictors of outcomes.

CONCLUSIONS

IB, DB/CB are relatively effective and safe revascularization options for pediatric MMD/MMS. Low-quality GRADE evidence suggests that DB/CB was associated with better long-term angiographic revascularization outcomes when compared with IB, although this did not translate to long-term stroke and mortality benefits.

[Factors of effective neovascularization after surgical treatment of moyamoya disease]

BACKGROUND

Moyamoya disease is a chronic cerebrovascular disease with complex pathophysiology. This disease is characterized by unique and unclear features of neoangiogenesis in natural course of disease and after surgical treatment. Natural collateral circulation was discussed in the first part of the article.

OBJECTIVE

To analyze the nature and degree of neoangiogenesis after combined revascularization in patients with moyamoya disease and to identify the factors of effective direct and indirect components.

MATERIAL AND METHODS

We analyzed 80 patients with moyamoya disease who underwent 134 surgical interventions. The main group consisted of patients after combined revascularization (79 operations), two control groups comprised patients after indirect (19) and direct (36) operations. We assessed postoperative MR data, function of each component of revascularization considering angiographic and perfusion modes and their contribution to the overall result of revascularization.

RESULTS

Factors of effective direct components of revascularization are large diameter of acceptor (p=0.028) and donor (p<0.0001) arteries, as well as double anastomoses (p=0.009). Factors of effective indirect synangiosis are younger age of patients (p=0.009), «ivy» symptom (p=0.005), enlargement of M4 branches of the MCA (p=0.026), transdural (p=0.004) and leptomeningeal (p=0.001) collaterals, use of more indirect components (p=0.027). Combined surgery provides the best angiographic (p=0.023) and perfusion (p<0.0001) results of revascularization. If one of the components is ineffective, other one ensures favorable result of surgery.

CONCLUSION

Combined revascularization is preferable in patients with moyamoya disease. However, a differentiated approach involving the effectiveness of various components of revascularization should be taken into account when planning surgical tactics. Understanding the state of collateral circulation in patients with moyamoya disease both in natural course of disease and after surgical treatment opens the ways for their rational use.

Wide Arterial Sparing Encephalo-Duro-Synangiosis for Moyamoya: Surgical Technique and Outcomes

BACKGROUND

Moyamoya is managed by surgical revascularization, but no standardized method has yet been universally adopted.

OBJECTIVE

To describe a new indirect bypass technique for pediatric moyamoya, wide arterial sparing encephalo-duro-synangiosis (WASEDS), which provides a much wider area of revascularization with minimal compromise to the middle meningeal arterial tree compared with traditional procedures. Initially used as a salvage technique after failed encephalo-duro-arterio-synangiosis, its success later motivated its use as a first-line procedure.

METHODS

Clinical and radiographic records of patients who underwent WASEDS for moyamoya from 2009 to 2020 were reviewed. Brain perfusion relative cerebral blood volume on the side of the WASEDS procedure was calculated. Two-tailed paired t tests were performed to identify the statistically significant differences ( P ≤ .05).

RESULTS

WASEDS was successfully performed on 8 patients for a total of 14 cerebral hemispheres. Age ranged from 2 to 25 years. There were no mortalities. The average clinical and radiographic follow-up was 49.79 months (range 2-126 months), demonstrating improvement in neurological condition and no postoperative stroke and significant diminution or cessation of transient ischemic attacks in all patients. Relative cerebral blood volume increased 9.24% after the WASEDS procedure ( P = .012). There were no neurological complications. There were 2 pseudomeningoceles related to the extensive dural openings.

CONCLUSION

WASEDS is a safe and effective indirect revascularization technique for both primary and salvage techniques. It provides an extensive area of cortical revascularization with no compromise of the middle meningeal vasculature and subjective reports of early improvement in cognition and behavior. The main disadvantage is elevated risk of pseudomeningocele secondary to the large craniotomy.

Short- and long-term outcomes of moyamoya patients post-revascularization

OBJECTIVE

The post-bypass stroke risk factors and long-term outcomes of moyamoya patients are not well documented. Therefore, the authors studied 30-day stroke risks and patients’ long-term physical, functional, and social well-being.

METHODS

This was a single-institution combined moyamoya disease (MMD) database interrogation and questionnaire study. From 1991 to 2014, 1250 revascularization procedures (1118 direct bypasses, 132 indirect bypasses) were performed in 769 patients. Completed questionnaires were received from and available for analysis on 391 patients, and 6-month follow-up data were available for 96.4% (741/769) of the patients.

RESULTS

The patients consisted of 548 females and 221 males, with a mean age of 32 years (range 1–69 years). Three hundred fifty-eight bypasses were performed in 205 pediatric patients (73% direct bypasses), and 892 revascularizations were performed in 564 adults (96% direct bypasses). Fifty-two patients (6.8%) developed major strokes with a worsening modified Rankin Scale (mRS) score within 30 days postoperatively. The 30-day major stroke risk was 5.3% (41/769) and 2.6% (12/467) after the first and second bypasses, respectively. Logistic regression analysis revealed that older age, modified MRI (mMRI) score, and hemodynamic reserve (HDR) score are clearly associated with higher postoperative stroke risks. Over a mean follow-up of 7.3 years (range 0.5–26 years), the long-term stroke risk among 741 patients was 0.6% per patient-year; 75% of these patients had excellent outcomes (mRS score 0–1). The long-term outcome questionnaire study showed that 84% (234/277) of patients reported resolution or improvement in their preoperative headache, 83% (325/391) remained employed or in school, and 87% (303/348) were self-caring.

CONCLUSIONS

In this large, single-center surgical series, most of the adult and pediatric patients had direct revascularization, with a 4.2% per-bypass-procedure (6.8% per patient) 30-day major stroke risk and a 0.6% per-patient-year long-term stroke risk. The authors identified various risk factors that are highly correlated with postoperative morbidity (age, mMRI score, and HDR score) and are involved in ongoing work to develop the predictive modeling for future patient selection and treatment.

A meta-analysis of comparisons of various surgical treatments for moyamoya diseases

PURPOSE

Ischemia is one of the most familiar complications in the different procedures for moyamoya disease (MMD), but the optimal surgical approaches for MMD remain unknown. We aimed to evaluate the efficiency of various surgical treatments.

METHODS

A literature search word was performed through four databases such as Cochrane Library, Web of Science, PubMed, and EMBASE for the literature published until May 2021. The I² statistic was used to assess heterogeneity. A random/fixed-effects model was used to pool.

RESULTS

There are a total of 18 studies including three surgical treatments such as including indirect, direct, and combined bypass in this study. The result revealed that indirect bypass was related to a higher incidence of recurrence stroke compared to the direct and combined bypass treatment (p = .001). Furthermore, the cases undergoing direct bypass were associated with a better angiographic change than the indirect bypass (OR = 3.254, p = .013).

CONCLUSION

This meta-analysis demonstrated a positive effect of using the direct and combined bypass to treat MMD compared to indirect bypass due to their lower rates of recurrence stroke.

[Combined cerebral revascularization for moyamoya disease]

INTRODUCTION

Combined cerebral revascularization with direct and indirect components is recognized as the most appropriate method for treating patients with Moyamoya disease all over the world, however, large studies on its effectiveness in Russia have not yet been conducted.

THE AIM OF THE STUDY

Was to evaluate the results of combined cerebral revascularization in patients with Moyamoya disease with an analysis of the clinical state and perfusion and angiographic features of neoangiogenesis.

MATERIAL AND METHODS

For the period from 2013 to 2020 in N.N. Burdenko National Medical Research Center of Neurosurgery 79 combined revascularizations were performed in 55 patients with Moyamoya disease. The average age was 13.9±10.11 years. All patients were examined according to a single protocol, including a comprehensive assessment of the clinical symptoms, the state of the brain tissue, the cerebral vascular system, and cerebral blood flow. The results of surgical treatment were evaluated in the early postoperative and long-term periods. The average follow-up period was 14.66±13.17 months. In the postoperative period, the dynamics of neurological status and cerebral blood flow were assessed and the features of neoangiogenesis from various components of revascularization were studied.

RESULTS

In the early postoperative period, in 77.2% of cases, a good treatment result was observed, with no negative dynamics of the neurological status. Ischemic stroke in the operated hemisphere developed in 4 cases (5.1%). In the follow-up period, an improvement in neurological symptoms was observed in 76.6%. Improvement of cerebral blood flow was noted in 92.4% of cases, direct anastomoses functioned in 94.3%, and signs of neovascularization in the area of indirect synangiosis were observed in 80.0%. At the same time, a complementary influence of direct and indirect components of revascularization was revealed in ensuring good general angiographic and perfusion results.

CONCLUSIONS

Combined revascularization is a highly effective method of surgical treatment of all patients with Moyamoya disease.

Failures in Revascularization for Pediatric Moyamoya Disease and Syndrome: A Scoping Review

BACKGROUND

Moyamoya disease (MMD) and moyamoya syndrome (MMS) are a rare cause of stroke commonly managed surgically. We conducted a scoping review to identify the current scope of the literature regarding factors associated with failure of revascularization surgery for MMD and MMS in pediatric patients and to catalyze future research.

METHODS

A scoping review was conducted to explore failures of revascularization surgery for MMD and MMS in pediatric patients using the PubMed, Embase, and Scopus databases. Titles and abstracts returned from searches were screened for full-text review. Studies meeting inclusion criteria were reviewed in full, and relevant data were extracted.

RESULTS

Of 2450 resultant articles, 15 were included. Angiographic outcomes were reported for 900 hemispheres, of which 442 (49.1%) were denoted as Matsushima grade A, 299 (33.2%) as Matsushima grade B, and 159 (17.7%) as Matsushima grade C. Patients with MMS had poorer angiographic outcomes than did patients with MMD. Patients with poor neovascularization had a greater degree of moyamoya vessels on follow-up angiogram. Suzuki stage was not associated with angiographic outcome in individual patients. Angiographic outcomes differed by surgical approach and were not associated with clinical outcomes. Literature identifying factors was sparse.

CONCLUSIONS

The existing literature indicates that factors such as cause, degree of moyamoya vessels, and surgical approach may affect the likelihood of Matsushima grade C revascularization in pediatric patients with MMD and MMS. Future studies are necessary to definitively elucidate factors associated with failure of revascularization surgery for pediatric MMD.

[Modern trends in diagnosis and surgical treatment of moyamoya disease]

This review is devoted to moyamoya disease. It is a rare chronic steno-occlusive cerebrovascular disease. However, moyamoya disease is increasingly diagnosed by neurosurgeons in our country. Unlike atherosclerotic lesions of cerebral arteries, pathogenesis and course of this disease are much more complex and variable. Therefore, specialists often have certain difficulties in diagnosis, management and treatment of these patients. To date, a large number of surgical interventions have been proposed for the treatment of moyamoya disease. Revascularization approaches include direct procedures (extra-intracranial microanastomoses), indirect methods (synangioses) and combined revascularization. The purpose of the review is to systematize current literature data on the pathogenesis, diagnosis, clinical patterns and surgical treatment of patients with moyamoya disease. results Outcomes of surgical revascularization and the role of its various components in combined approach are under particular attention.

Lessons Learned from the Initial Experience with Pedicled Temporoparietal Fascial Flap for Combined Revascularization In Moyamoya Angiopathy: A Case Series

BACKGROUND

The pedicled temporoparietal fascial flap (TPFF) with a direct superficial temporal (STA) artery to middle cerebral artery (MCA) bypass is a novel combined revascularization approach for moyamoya angiopathy (MMA). With this case series, we aim to report the initial experience with pedicled TPFF combined revascularization for MMA treatment.

METHODS

Data from 14 consecutive patients undergoing pedicled TPFF combined revascularization for MMA between May 2016 and December 2018 were retrospectively reviewed. Patients admitted with acute ischemia or a modified Rankin Scale (mRS) score >3 were considered high risk.

RESULTS

Mean ± standard deviation age on surgery was 41.9 ± 15.4 years. Three of 14 patients (21.4%) presented with an mRS score >3. Nine of 14 patients (64.3%) presented with ischemic stroke, 4 of whom (44.4%) had acute ischemia. Direct anastomosis patency was confirmed in all cases postoperatively. Mean hospitalization time was 13 ± 9.3 days and mean follow-up time was 14.1 ± 9.3 months. From admission to follow-up, neurologic status improved in 8 patients (57.1%) and stabilized in 6 patients (42.9%). Overall, 11/14 patients (78.6%) achieved good functional outcome (mRS score ≤2). All patients achieved some radiographic collateral development, with 5 (71.5%) graded as Matsushima A and B. Three patients developed new radiographic ischemia and 3 experienced wound complications, all in the high-risk group.

CONCLUSIONS

The TPFF combined approach is a viable strategy for revascularization in MMA. This technique may be suboptimal in patients presenting with acute ischemia and/or mRS score >3.

Superficial temporal artery-to-middle cerebral artery bypass in combination with indirect revascularization in moyamoya patients ≤ 3 years of age

OBJECTIVE Revascularization is indicated in the management of moyamoya disease (MMD), with options that include direct and indirect techniques. Indirect bypass is popular in young children because the diminutive caliber of donors and recipients makes direct bypass difficult. The authors reviewed a series of patients treated with direct superficial temporal artery (STA)–to–middle cerebral artery (MCA) bypass in combination with encephalomyosynangiosis (EMS) in children 3 years or younger to demonstrate feasibility and safety. METHODS A retrospective review of all surgeries for MMD over a 19-year period identified 11 procedures in 6 patients. Surgical results, angiographic outcomes, and clinical outcomes were analyzed. RESULTS Patients had a mean age of 22.4 months. The symptomatic hemisphere was revascularized first, and the contralateral hemisphere was revascularized on average 2.8 months later in 5 patients. All direct bypasses were patent postoperatively and remained patent at late follow-up (mean 4.1 years), with both STA and MCA diameters increasing significantly (n = 5, p < 0.03). At last follow-up (mean follow-up duration, 5.0 years), favorable outcomes (modified Rankin Scale scores 0–2) were observed in 5 of the 6 patients (83%), with 1 dependent patient remaining unchanged postoperatively. CONCLUSIONS Direct STA-MCA bypass in combination with EMS for MMD is feasible and safe in patients 3 years or younger, based on favorable clinical and radiological outcomes in this patient cohort. Direct bypass should be considered when immediate revascularization is needed, without the biological delay associated with indirect bypass. ABBREVIATIONS EDAS = encephaloduroarteriosynangiosis; EMS = encephalomyosynangiosis; MCA = middle cerebral artery; MMD = moyamoya disease; mRS = modified Rankin Scale; STA = superficial temporal artery; TIA = transient ischemic attack.

Late Cerebrovascular Events and Social Outcome after Adolescence: Long-term Outcome of Pediatric Moyamoya Disease

In this article, the authors review the literature related to long-term outcome of pediatric moyamoya disease, focusing on late cerebrovascular events and social outcome of pediatric patients once they reach adulthood. Late-onset de novo hemorrhage is rare but more serious than recurrence of ischemic stroke. Long-term follow-up data on Asian populations suggest that the incidence of de novo hemorrhage might increase at age 20 or later, even more than 10 years after bypass surgery. Social adaptation difficulty, possibly related to cognitive impairment caused by frontal ischemia, continues in 10-20% of patients after they reach adulthood, even if no significant disability is present in daily life. A treatment strategy aimed at improving long-term outcome and careful follow-up might be required.

[Revascularization experience and results in ischaemic cerebrovascular disease: Moyamoya disease and carotid occlusion]

INTRODUCTION

Cerebral revascularization techniques are an indispensable tool in the current armamentarium of vascular neurosurgeons. We present revascularization surgery experience and results in both moyamoya disease and occlusive cerebral ischaemia.

PATIENTS AND METHODS

Patients with ischaemic occlusive disease and moyamoya disease who underwent microsurgical revascularization between October 2014 and September 2017 were analysed.

RESULTS

In the study period, 23 patients with occlusive ischaemic disease underwent microsurgical revascularization. Three patients presented with serious postoperative complications (2 intraparenchymal haemorrhages in the immediate postoperative period and one thrombosis of the femoral artery). All patients, except one, achieved normalization of the cerebral hemodynamic reserve (CHR) in the SPECT study. Twenty patients had a good neurological result, with no ischaemic recurrence of the revascularized territory. Among patients with moyamoya, 20 had moyamoya disease and 5 had moyamoya syndrome with unilateral involvement. Five patients were treated at paediatric age. Haemorrhagic onset occurred in 2 patients. The CHR study showed hemodynamic compromise in all patients. Cerebral SPECT at one year showed resolution of the hemodynamic failure in all patients. There have been 4 postoperative complications (acute subdural hematoma, two subdural collections and one dehiscence of the surgical wound). No patient presented with neurological worsening at 6 and 12months of follow-up.

CONCLUSIONS

Cerebral revascularization through end-to-side anastomosis between the superficial temporal artery and a cortical branch of the middle cerebral artery is an indisputable technique in the treatment of moyamoya disease and possibly in a subgroup of patients with symptomatic occlusive ischaemic cerebrovascular disease.

Evaluation of Encephaloduroarteriosynangiosis Efficacy Using Probabilistic Independent Component Analysis Applied to Dynamic Susceptibility Contrast Perfusion MRI

BACKGROUND AND PURPOSE

Indirect cerebral revascularization has been successfully used for treatment in Moyamoya disease and symptomatic intracranial atherosclerosis. While angiographic neovascularization has been demonstrated after surgery, measurements of local tissue perfusion are scarce and may not reflect the reported successful clinical outcomes. We investigated probabilistic independent component analysis and conventional perfusion parameters from DSC-MR imaging to measure postsurgical changes in tissue perfusion.

MATERIALS AND METHODS

In this prospective study, 13 patients underwent unilateral indirect cerebral revascularization and DSC-MR imaging before and after surgery. Conventional perfusion parameters (relative cerebral blood volume, relative cerebral blood flow, and TTP) and probabilistic independent components that reflect the relative contributions of DSC signals consistent with arterial, capillary, and venous hemodynamics were calculated and examined for significant changes after surgery. Results were compared with postsurgical DSA studies to determine whether changes in tissue perfusion were due to postsurgical neovascularization.

RESULTS

Before surgery, tissue within the affected hemisphere demonstrated a high probability for hemodynamics consistent with venous flow and a low probability for hemodynamics consistent with arterial flow, whereas the contralateral control hemisphere demonstrated the reverse. Consistent with symptomatic improvement, the probability for venous hemodynamics within the affected hemisphere decreased with time after surgery (P = .002). No other perfusion parameters demonstrated this association. Postsurgical DSA revealed an association between an increased preoperative venous probability in the symptomatic hemisphere and neovascularization after surgery.

CONCLUSIONS

Probabilistic independent component analysis yielded sensitive measurements of changes in local tissue perfusion that may be associated with newly formed vasculature after indirect cerebral revascularization surgery.

Rapid resolution of brain ischemic hypoxia after cerebral revascularization in moyamoya disease

BACKGROUND

In moyamoya disease (MMD), cerebral revascularization is recommended in patients with recurrent or progressive ischemic events and associated reduced cerebral perfusion reserve. Low-flow bypass with or without indirect revascularization is generally the standard surgical treatment. Intraoperative monitoring of cerebral partial pressure of oxygen (PtiO2) with polarographic Clark-type probes in cerebral artery bypass surgery for MMD-induced chronic cerebral ischemia has not yet been described.

OBJECTIVE

To describe basal brain tissue oxygenation in MMD patients before revascularization as well as the immediate changes produced by the surgical procedure using intraoperative PtiO2 monitoring.

METHODS

Between October 2011 and January 2013, all patients with a diagnosis of MMD were intraoperatively monitored. Cerebral oxygenation status was analyzed based on the Ptio2/PaO2 ratio. Reference thresholds of PtiO2/PaO2 had been previously defined as below 0.1 for the lower reference threshold (hypoxia) and above 0.35 for the upper reference threshold (hyperoxia).

RESULTS

Before STA-MCA bypass, all patients presented a situation of severe tissue hypoxia confirmed by a PtiO2/PaO2 ratio <0.1. After bypass, all patients showed a rapid and sustained increase in PtiO2, which reached normal values (PtiO2/PaO2 ratio between 0.1 and 0.35). One patient showed an initial PtiO2 improvement followed by a decrease due to bypass occlusion. After repeat anastomosis, the patient's PtiO2 increased again and stabilized.

CONCLUSION

Direct anastomosis quickly improves cerebral oxygenation, immediately reducing the risk of ischemic stroke in both pediatric and adult patients. Intraoperative PtiO2 monitoring is a very reliable tool to verify the effectiveness of this revascularization procedure.

Quantitative Digital Subtraction Angiography in Pediatric Moyamoya Disease

Moyamoya disease is a unique cerebrovascular disorder characterized by idiopathic progressive stenosis at the terminal portion of the internal carotid artery (ICA) and fine vascular network. The aim of this review is to present the clinical application of quantitative digital subtraction angiography (QDSA) in pediatric moyamoya disease. Using conventional angiographic data and postprocessing software, QDSA provides time-contrast intensity curves and then displays the peak time (T_max) and area under the curve (AUC). These parameters of QDSA can be used as surrogate markers for the hemodynamic evaluation of disease severity and quantification of postoperative neovascularization in moyamoya disease.

[Learning vascular microsurgical techniques on an animal model]

INTRODUCTION

The aim of this study was to assess the progress of an operator, during microsurgical training, on a bilateral carotid revascularization in the rat.

MATERIAL AND METHODS

In this prospective study, nine rats underwent bilateral carotid revascularization. An end-to-end graft of the right carotid artery by the facial vein and an end-to-side bypass of left carotid artery by the jugular external vein were performed. Anastomoses were carried out with 10/0 thread, based on the technique of the symmetric bi-angulation. At the end of procedure, a permeability test was performed on each anastomosis. Duration of survival of the animal, permeability of anastomosis, and evolution of the operating periods during the training were collected and respectively analyzed with a Fisher's and Student's t tests. In cases of procedure success, anastomoses were remotely controlled and a brain dissection was performed in order to seek a possible ischemia due to carotid clamping. In the event of failure, the rat was sacrificed and anastomoses were opened in order to establish the cause of thrombosis.

RESULTS

Two thirds of the revascularization procedures were successful. A total of 83.3% of the anastomoses were patent. Of the six rats preserved for remote evaluation of anastomoses, three died. Remotely controlled anastomoses remained all permeable. No cerebral ischemia, associated with carotid clamping (approximately 45 minutes), was highlighted by brain dissection. With the growing experience of the operator, an improvement in results in mastery of the technique was objectively observed. Operative durations were reduced between the beginning and the end of the training: -54 minutes (P=0.001).

CONCLUSION

Microsurgical laboratory training seems to be essential in order to acquire the dexterity, ease and experience necessary for performing microsurgical procedures in humans.

Indirect cerebral revascularization with a temporoparietal fascial flap in pediatric moyamoya patients: a novel technique and review of current surgical options

Moyamoya syndrome is a progressive occlusive disease of the cerebral vessels. There are a variety of surgical treatments directed at revascularizing the ischemic brain in pediatric moyamoya disease. Many reports of varying success with both direct and indirect type of procedures can be found in medical literature. We present a novel technique, encephalo-TPF-synangiosis (ETS) with a pedicled bone flap, for indirect moyamoya revascularization in pediatric patients. A three-quarters osteoplastic temporal craniotomy was created. A pedicled temporoparietal fascial flap was passed intracranially through the temporalis muscle and placed into contact with the pial surface. The bone flap was the reaffixed to the skull. We performed 8 ETS in 6 patients. This is a well-vascularized, highly reliable method that offers broad-based surface area for revascularization. We also offer a composite overview of current surgical indirect revascularization techniques.

Combined Direct and Indirect Bypass for Moyamoya

BACKGROUND:

The optimal revascularization strategy for symptomatic adult moyamoya remains controversial. Whereas direct bypass offers immediate revascularization, indirect bypass can effectively induce collaterals over time.

OBJECTIVE:

Using angiography and quantitative magnetic resonance angiography, we examined the relative contributions of direct and indirect bypass in moyamoya patients after combined direct superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass and indirect encephaloduroarteriosynangiosis (EDAS).

METHODS:

A retrospective review of moyamoya patients undergoing combined STA-MCA bypass and EDAS was conducted, excluding pediatric patients and hemorrhagic presentation. Patients with quantitative magnetic resonance angiography measurements of the direct bypass immediately and &gt; 6 months postoperatively were included. Angiographic follow-up, when available, was used to assess EDAS collaterals at similar time intervals.

RESULTS:

Of 16 hemispheres in 13 patients, 11 (69%) demonstrated a significant (&gt; 50%) decline in direct bypass flow at &gt; 6 months compared with baseline, averaging a drop from 99 ± 35 to12 ± 7 mL/min. Conversely, angiography in these hemispheres demonstrated prominent indirect collaterals, in concert with shrinkage of the STA graft. Decline in flow was apparent at a median of 9 months but was evident as early as 2 to 3 months.

CONCLUSION:

In this small cohort, a reciprocal relationship between direct STA bypass flow and indirect EDAS collaterals frequently occurred. This substantiates the notion that combined direct/indirect bypass can provide temporally complementary revascularization.

History of the development of surgical treatments for moyamoya disease

Many surgical treatments for moyamoya disease have been developed over the past 40 years. The optimum treatment for ischemic-type moyamoya disease is almost established. The first surgical treatment for the disease was the superficial temporal artery to middle carotid artery (STA-MCA) anastomosis. The discovery of spontaneous collateral formation following the STA-MCA anastomosis surgery led to the development of various indirect bypass procedures. Collateral formation and clinical outcomes from direct and indirect procedures have been compared to assess the merits and limitations of each technique. Experience and a greater understanding of the surgical effects of moyamoya disease have led to the development of surgical procedures combining various direct and indirect bypass techniques for optimal restoration of perfusion. This review of the historical development and efficacy of each procedure will aid surgeons in selecting the most appropriate surgical procedure for patients of different ages with different symptoms and disease severities.

Intracranial arterial stenoses: current viewpoints, novel approaches, and surgical perspectives

Ten percent of all strokes occurring in the USA are caused by intracranial arterial stenosis (IAS). Symptomatic IAS carries one of the highest rates of recurrent stroke despite intensive medical therapy (25 % in high-risk groups). Clinical results for endovascular angioplasty and stenting have been disappointing. The objectives of this study were to review the contemporary understanding of symptomatic IAS and present potential alternative treatments to resolve factors not addressed by current therapies. We performed a literature review on IAS pathophysiology, natural history, and current treatment. We present an evaluation of the currently deficient aspects in its treatment and explore the role of alternative surgical approaches. There is a well-documented interrelation between hemodynamic and embolic factors in cerebral ischemia caused by IAS. Despite the effectiveness of medical therapy, hemodynamic factors are not addressed satisfactorily by medications alone. Collateral circulation and severity of stenosis are the strongest predictors of risk for stroke and death. Indirect revascularization techniques, such as encephaloduroarteriosynangiosis, offer an alternative treatment to enhance collateral circulation while minimizing risk of hemorrhage associated with hyperemia and endovascular manipulation, with promising results in preliminary studies on chronic cerebrovascular occlusive disease. Despite improvements in medical management for IAS, relevant aspects of its pathophysiology are not resolved by medical treatment alone, such as poor collateral circulation. Surgical indirect revascularization can improve collateral circulation and play a role in the treatment of this condition. Further formal evaluation of indirect revascularization for IAS is a logical and worthy step in the development of intracranial atherosclerosis treatment strategies.

Indirect revascularization for nonmoyamoya intracranial arterial stenoses: clinical and angiographic outcomes

OBJECT

Symptomatic intracranial arterial stenoses have a high rate of recurrent stroke despite medical and endovascular treatments. The authors present clinical and angiographic quantitative outcomes of indirect revascularization for patients with symptomatic intracranial stenosis.

METHODS

Patients treated for symptomatic intracranial arterial stenosis by indirect revascularization were included. The patient population comprised those in whom medical management had failed and for whom endovascular therapy was unsuitable or had failed. Patients underwent encephaloduroarteriosynangiosis (EDAS) with or without bur holes. Preoperative and postoperative angiograms were evaluated for change in caliber of extracranial blood vessels (superficial temporal artery [STA] and middle meningeal artery [MMA]) and for evidence of neovascularization.

RESULTS

Thirteen patients underwent EDAS. Ischemic symptoms ceased within the follow-up period in all patients, returning in a delayed fashion in only 2. No other patients had recurrent TIAs or strokes after the initial postoperative period. Donor blood vessels increased in size relative to preoperative sizes in all but 1 case (average increase of 52% for proximal STA [p=0.01], 74% for midpoint of STA [p=0.01], and 84% for the MMA [p=0.02]). In addition, 8 of 11 patients demonstrated direct spontaneous anastomoses from extracranial to middle cerebral artery branches, and all patients demonstrated angiographic evidence of vascular blush and/or new branches from the STA and/or MMA.

CONCLUSIONS

Indirect revascularization appears to be a safe and effective method to improve blood flow to ischemic brain due to intracranial arterial stenosis. Neovascularization and enlargement of the branches of the ECA were observed in all patients and correlated with improvement in ischemic symptoms. Indirect revascularization is an option for patients in whom medical therapy has failed and who are not suitable for endovascular treatment.

Effect of mouth opening on bypass function after combined revascularization for Moyamoya disease

Moyamoya disease represents a rare steno-occlusive disease of the internal carotid artery (ICA) with a reactive and pathological basal network of collateral vessels. It may lead to ischemic stroke or intracerebral hemorrhage. Treatment options are either direct or indirect revascularization procedures or a combination thereof. Specialized centers report sufficient revascularization in most patients and low complication rates.Between 2005 and 2008, direct extra-intracranial bypass surgery in combination with encephalomyosynangiosis (EMS) was performed in 71 Moyamoya patients at the Mannheim University Medical Center.Following one case of reversible neurological deficits associated with mouth opening, we prospectively evaluated the effect of mouth opening on bypass function in this patient and four further consecutive patients by digital subtraction angiography.Three out of five patients showed alterations in bypass patency upon mouth opening. The obstruction was located at the junction of the bypass and the temporal muscle. Two temporary occlusions and one case of decreased flow were observed. One patient demonstrated reversible hemiparesis and aphasia.

Severely impaired cerebrovascular reserve in patients with cerebral proliferative angiopathy

OBJECT

Cerebral proliferative angiopathy (CPA) has been morphologically distinguished from classically appearing brain arteriovenous malformations (AVMs) by exhibition of functional brain parenchyma that is intermingled with abnormal vascular channels. The presence of oligemia in this intralesional brain tissue may suggest ischemia, which is not detected in classic brain AVMs. The authors hypothesized that patients with CPA would exhibit a greater impairment of cerebrovascular reserve in neuronal tissue surrounding the true nidus compared with those with brain AVMs.

METHODS

Four patients with CPA, 10 patients with brain AVMs and seizures, and 12 young healthy individuals were studied. The 4 patients with CPA underwent blood oxygen level-dependent MR imaging examinations while applying normoxic step changes in end-tidal CO(2) to obtain quantitative cerebrovascular reactivity measurements.

RESULTS

Patients with a CPA lesion exhibited severely impaired perilesional cerebrovascular reserve in comparison with patients with brain AVMs and seizures (0.10 ± 0.03 vs 0.16 ± 0.03, respectively; p < 0.05), and young healthy individuals (0.10 ± 0.03 vs 0.21 ± 0.06, respectively; p < 0.01).

CONCLUSIONS

This study demonstrated severely impaired cerebrovascular reserve in the perilesional brain tissue surrounding the abnormal vessels of patients with CPA. This finding may provide an additional means to distinguish CPA from classic brain AVMs.

Outcome of repeat revascularization surgery for moyamoya disease after an unsuccessful indirect revascularization

Object

Revascularization for moyamoya disease, either by direct anastomosis or indirect procedures, is an accepted and effective form of treatment for prevention of future ischemic events. Indirect procedures do not provide sufficient collateral vessels in a subset of patients, who then have persistent or new symptoms. Repeat revascularization procedures may be recommended for these patients.

Methods

Sixteen patients underwent repeat revascularization after undergoing an indirect procedure in the same hemisphere. These patients were included in the study, and a retrospective review of their clinical details, neuroimaging results, surgical details, and outcome was performed. Direct revascularization was the procedure of choice; however, in patients with no acceptable recipient vessel (> 0.6 mm) the authors added a second indirect procedure for further revascularization.

Results

Over the last 19 years, 16 patients (8 male and 8 female patients, age range 5–48 years, mean 16.7 years, 10 pediatric and 6 adult patients) underwent repeat revascularization for moyamoya disease. Initially all patients presented with ischemic symptoms (4 transient ischemic attacks [TIAs] and 12 strokes; 2 patients had bilateral symptoms). Angiography revealed that 13 patients had bilateral disease, and 3 had unilateral disease. Initial surgery was bilateral encephaloduroarteriosynangiosis (EDAS) in 9, unilateral EDAS alone in 3, unilateral EDAS with contralateral superficial temporal artery–middle cerebral artery (STA-MCA) bypass in 2, bilateral encephalomyosynangiosis (EMS) in 1, and unilateral EMS in 1. Thirteen of the 16 patients continued to have TIAs in the hemisphere ipsilateral to surgery, whereas 1 patient had seizures and cognitive deficit, 1 had asymptomatic infarct on MR imaging, and 1 had visual symptoms. Poor revascularization was seen on angiography studies in all patients. The median duration between the surgeries was 24 months (3 months–10 years).

Repeat revascularization was performed in 23 hemispheres (16 patients). Direct revascularization was performed in 14 hemispheres (60.9%): STA-MCA bypass in 10, external carotid artery–MCA vein bypass in 2, occipital artery (OA)–MCA in 1, and OA–posterior cerebral artery in 1 hemisphere. Indirect revascularization was performed for patients without an acceptable recipient vessel, and was done in 9 hemispheres. The procedures included EMS (4 hemispheres), repeat EDAS (2), and omental transposition (3). There was 1 postoperative death in a patient undergoing a high-flow vein graft implantation. None of the other patients experienced any neurological worsening after surgery.

Follow-up was available in all patients, ranging from 3 to 144 months (mean 34 months, median 12 months). Of the 15 patients who survived repeat revascularization surgery, 12 (80%) were free from any TIA, stroke, or any other neurological symptoms. Two patients had occasional TIAs, less frequent than before, whereas 1 patient had frequent TIAs and underwent revision of the revascularization. Angiographic studies were available in 11 patients, and showed improved flow in the hemispheres in 10 patients. Follow-up MR imaging performed at 6 months did not reveal a new infarct in any patient.

Conclusions

Repeat revascularization procedures are effective for patients who are clinically symptomatic and have inadequate collateral vessels following indirect procedures. Although direct procedures are preferred, the choice of procedure depends on the operative findings and the status of donor and recipient vessels.

Clinical and angiographic outcomes from indirect revascularization surgery for Moyamoya disease in adults and children: a review of 63 procedures

BACKGROUND

Several forms of indirect cerebral revascularization have been proposed to promote neovascularity to the ischemic brain.

OBJECTIVE

To present clinical and angiographic outcomes of indirect revascularization by encephaloduroarteriosynangiosis and burr holes for the treatment of Moyamoya disease in adults and children.

METHODS

Data from 63 hemispheres treated in 42 patients (average age, 30 years; 33 adults; 30 female patients; median follow-up, 14 months) were reviewed. In hemispheres with preoperative and postoperative (6- to 12-month) angiograms available, superficial temporal artery (STA) and middle meningeal artery (MMA) diameters were measured. Preoperative and postoperative corrected arterial sizes were compared.

RESULTS

Seven patients (17%) had transient ischemic attacks that resolved within 1 month of surgery. No patients suffered moyamoya-related hemorrhage after treatment. Two patients developed additional symptoms many years after surgery. In 18 hemispheres with preoperative and postoperative angiograms, there was an average postoperative increase in STA and MMA diameters of 51% (P = .003) and 49% (P = .002), respectively. Both children and adults displayed revascularization. Two patients did not demonstrate increased vessel size. STA blush and new branches and MMA blush and new branches were identified in 12, 14, 14, and 16 hemispheres, respectively. Angiographic blush was identified in 59% of frontal and 19% of parietal burr holes (P = .03). Surgical complications included 2 subdural hemorrhages requiring evacuation and 2 new ischemic deficits (1 transient).

CONCLUSION

Indirect revascularization by encephaloduroarteriosynangiosis and burr holes for moyamoya results in long-term resolution of ischemic and hemorrhagic manifestations in 95% of adults and children. The MMA appears to contribute significantly to the revascularization on follow-up angiograms with increased size and neovascularity comparable to that of the STA. Angiographically, parietal burr holes do not contribute as significantly as frontal burr holes.

Indirect revascularization techniques for treating moyamoya disease

There have been many indirect revascularization techniques described by surgeons for the treatment of moyamoya disease. These surgical procedures are typically used more commonly in pediatric, than in adults', cases. Some of the techniques include: cervical sympathectomy, omental transplantation, multiple burr holes, encephalo-myo-synangiosis (EMS), encephalo-arterio-synangiosis (EAS), encephalo-duro-synangiosis (EDS), encephalo-myo-arterio-synangiosis (EMAS), encephalo-duro-arterio-synangiosis (EDAS), encephalo-duro-arterio-myo-synangiosis (EDAMS), encephalo-duro-galeo (periosteal)-synangiosis (EDGS), and combinations of all the above. This chapter will detail the technical aspects of many of these procedures and some of the reported clinical outcomes.

Intraoperative blood flow analysis of direct revascularization procedures in patients with moyamoya disease

Moyamoya disease is characterized by the progressive stenosis and often occlusion of the terminal internal carotid arteries, which leads to ischemic and hemorrhagic injuries. The etiology is unknown and surgical revascularization remains the mainstay treatment. We analyzed various hemodynamic factors in 292 patients with moyamoya disease, representing 496 revascularization procedures, including vessel dimension and intraoperative blood flow, using a perivascular ultrasonic flowprobe. Mean middle cerebral artery (MCA) flow rate was 4.4 ± 0.26 mL/min. After superficial temporal artery (STA)-MCA bypass surgery, flows at the microanastomosis were increased fivefold to a mean of 22.2 ± 0.8 mL/min. The MCA flows were significantly lower in the pediatric (16.2 ± 1.3 mL/min) compared with the adult (23.9 ± 1.0 mL/min; P<0.0001) population. Increased local flow rates were associated with clinical improvement. Permanent postoperative complications were low (<5%), but very high postanastomosis MCA flow was associated with postoperative stroke (31.2 ± 6.8 mL/min; P=0.045), hemorrhage (32.1 ± 10.2 mL/min; P=0.045), and transient neurologic deficits (28.6 ± 5.6 mL/min; P=0.047) compared with controls. Other flow and vessel dimension data are presented to elucidate the hemodynamic changes related to the vasculopathy and subsequent to surgical intervention.

Understanding and treating moyamoya disease in children

Moyamoya disease, a known cause of pediatric stroke, is an unremitting cerebrovascular occlusive disorder of unknown etiology that can lead to devastating, permanent neurological disability if left untreated. It is characterized by progressive stenosis of the intracranial internal carotid arteries and their distal branches and the nearly simultaneous appearance of basal arterial collateral vessels that vascularize hypoperfused brain distal to the occluded vessels. Moyamoya disease may be idiopathic or may occur in association with other syndromes. Most children with moyamoya disease present with recurrent transient ischemic attacks or strokes. Although there is no definitive medical treatment, numerous direct and indirect revascularization procedures have been used to improve the compromised cerebral circulation, with outcomes varying according to procedure type. Such techniques improve the long-term outcome of patients with both idiopathic and syndrome-associated moyamoya disease. This review provides a comprehensive discussion of moyamoya disease in children, with an emphasis on the most effective surgical treatment options.

Age-dependent revascularization patterns in the treatment of moyamoya disease in a European patient population

Object

Different revascularization procedures are used in the treatment of patients with moyamoya disease (MMD). The aim of this study was to investigate the relative contribution of direct and indirect revascularization procedures to the restoration of collateral blood supply in adult and pediatric patients with MMD.

Methods

The authors performed 39 combined cerebral revascularization procedures (standard extraintracranial bypass [STA-MCA bypass] plus encephalomyosynangiosis [EMS]) in 10 pediatric and 10 adult patients. All patients underwent physical examination and digital subtraction angiography before and 6 months after surgery. The STA-MCA bypass and EMS function were graded as Grade I (poor), II (moderate), or III (good) on the basis of the angiograms.

Results

In pediatric patients, bypass function was Grade I in 12, Grade II in 8, and Grade III in 0 hemispheres; EMS function was Grade I in 0, Grade II in 12, and Grade III in 8 hemispheres. In the adult patients, bypass function was Grade I in 8, Grade II in 8, and Grade III in 3 hemispheres; EMS function was Grade I in 10 hemispheres, Grade II in 5, and Grade III in 1 hemisphere. In the pediatric patients disease was classified as improved in 14 hemispheres on the basis of clinical results and stable in 6. In the adults it was classified as improved in 12 hemispheres stable in 7 hemispheres.

Conclusions

Combined revascularization led to good angiographic and clinical results in both patient populations. Especially in pediatric patients, EMS represents a suitable alternative to bypass surgery.

Surgical management of moyamoya syndrome

Moyamoya syndrome, a vasculopathy characterized by chronic progressive stenosis at the apices of the intracranial internal carotid arteries, is an increasingly recognized entity which is associated with cerebral ischemia. Diagnosis is made on the basis of clinical and radiographic findings, including a characteristic stenosis of the internal carotid arteries in conjunction with abundant collateral vessel development. Adult moyamoya patients often present with hemorrhage, leading to rapid diagnosis. In contrast, children usually present with transient ischemic attacks or strokes, which may prove more difficult to diagnose because of patient's inadequate verbal and other skills, leading to delayed recognition of the underlying moyamoya. The progression of disease can be slow, with rare, intermittent events, or it can be fulminant, with rapid neurologic decline. However, regardless of the course, it is apparent that moyamoya syndrome, both in terms of arteriopathy and clinical symptoms, inevitably progresses in untreated patients. Surgery is generally recommended for the treatment of patients with recurrent or progressive cerebral ischemic events and associated reduced cerebral perfusion reserve. Many different operative techniques have been described, all with the main goal of preventing further ischemic injury by increasing collateral blood flow to hypoperfused areas of the cortex, using the external carotid circulation as a donor supply. This article discusses the various treatment approaches, with an emphasis on the use of pial synangiosis, a method of indirect revascularization. The use of pial synangiosis is a safe, effective, and durable method of cerebral revascularization in moyamoya syndrome and should be considered as a primary treatment for moyamoya, especially in the pediatric population.

Moyamoya angiopathy in Europe

Over the past 6 years we at the Neurosurgery Department in Zürich have had the opportunity to manage increasing numbers of patients, especially children, with Moyamoya angiopathy. With increasing awareness of presence of this angiopathy in Europe the number of referrals from all across Europe is constantly on the increase. We have also been able to readdress the presence of the entity of Moyamoya angiopathy i.e. both the Moyamoya disease and the Moyamoya syndrome in the European population. Thorough presurgical workup is mandatory for evaluation of surgical candidates for the type of effective revascularisation procedure and therefore for their successful management. Apart from scrutinizing the routine yet indispensable presenting symptomatology with clinical examination of the patients, our preoperative diagnostic workup mainly consists of a 6 vessel cerebral angiography, cerebral perfusion studies with HMPAO-SPECT and H(2)15O-PET examinations and transcranial Doppler. Longterm follow-up of these patients is indispensable and of great interest to us in terms of etiology and progression of the disease process as well as the choice of effective revascularisation procedure especially in our European population.

Moyamoya disease in a Hispanic child: a case report

BACKGROUND

Moyamoya disease was initially described by Suzuki and Takaku in 1963 as a radiographic phenomenon relating to the tiny collateral vessels characteristic of the disease that resemble a cloud or puff of smoke. The disease is rare and initially it was believed that the disease was confined to the Japanese population. It consists of occlusive vascular disease at the Circle of Willis with a tendency toward multiple ischemic neurological events and small strokes. In older populations it can often be associated with further vascular degeneration and intracerebral hemorrhage. This paper discusses the diagnosis, treatment, and management of moyamoya disease in a Hispanic child.

CASE DESCRIPTION

The case of a Hispanic child who presented with transient ischemic attacks over a period of 1 year is reported. Magnetic resonance imaging (MRI) revealed occlusive vascular disease in the posterior Circle of Willis. Digital subtraction cerebral angiography showed vascular occlusion at the base of the skull with collateral leptomeningeal and posterior circulation contribution in a pattern typical of moyamoya disease. Technetium was injected for a SPECT study demonstrating less uptake in the left frontal and left parieto-occipital regions. The patient underwent a left superficial temporal-to-middle cerebral artery anastamosis followed by a right-sided anastamosis in a second operation. The patient tolerated the cerebral revascularization and was symptom-free at 6-month follow-up. Cerebral angiography demonstrated improved perfusion in both cerebral hemispheres postoperatively.

CONCLUSION

This article reports the occurrence of moyamoya in a Hispanic child. It illustrates the improved perfusion postoperatively as seen on digital subtraction cerebral angiography. Direct revascularization is felt to be difficult in children and alternatives such as encephaloduroarteriosynangiosis have been advocated. Direct revascularization was effective in treating moyamoya disease in this instance. Most of the discussion of moyamoya disease has been focused on the Japanese and Far East population. This report confirms the entity as occurring in a Hispanic individual in the United States with no known Japanese ancestry.

Rational approach to treatment of moyamoya disease in childhood

Early diagnosis and treatment of moyamoya disease in children is essential to minimize residual mental and physiologic deficits. Current treatment of childhood moyamoya disease in Japan, preoperative evaluation of perfusion reserve as a surgical indication, and the role of noninvasive follow-up by magnetic resonance angiography are reported. Approximately 20% of children with definite moyamoya disease were observed or treated medically. Among surgical procedures, single indirect bypass surgery was used in approximately 30% of all patients; combinations of direct and indirect bypass surgery, 20%; and multiple-indirect bypass surgery, 18%. Both adequate understanding of the primary condition and determination of optimal treatment, including specific operative procedures, required evaluation of cerebral circulation and metabolism. Surgical indications included reduced perfusion reserve in affected brain by positron emission tomography or single photon emission tomography with administration of acetazolamide or a CO2 load. Postoperative improvements of cerebral perfusion reserve show better correlation with disappearance of ischemic attacks than does angiographically demonstrated collateral formation. Follow-up evaluation with magnetic resonance angiography has advantages over conventional angiography because it is noninvasive and avoids general anesthesia.